Plan 9 from Bell Labs’s /usr/web/sources/plan9/sys/src/libdraw/arith.c

 ``` #include #include #include Point Pt(int x, int y) { Point p; p.x = x; p.y = y; return p; } Rectangle Rect(int x, int y, int bx, int by) { Rectangle r; r.min.x = x; r.min.y = y; r.max.x = bx; r.max.y = by; return r; } Rectangle Rpt(Point min, Point max) { Rectangle r; r.min = min; r.max = max; return r; } Point addpt(Point a, Point b) { a.x += b.x; a.y += b.y; return a; } Point subpt(Point a, Point b) { a.x -= b.x; a.y -= b.y; return a; } Rectangle insetrect(Rectangle r, int n) { r.min.x += n; r.min.y += n; r.max.x -= n; r.max.y -= n; return r; } Point divpt(Point a, int b) { a.x /= b; a.y /= b; return a; } Point mulpt(Point a, int b) { a.x *= b; a.y *= b; return a; } Rectangle rectsubpt(Rectangle r, Point p) { r.min.x -= p.x; r.min.y -= p.y; r.max.x -= p.x; r.max.y -= p.y; return r; } Rectangle rectaddpt(Rectangle r, Point p) { r.min.x += p.x; r.min.y += p.y; r.max.x += p.x; r.max.y += p.y; return r; } int eqpt(Point p, Point q) { return p.x==q.x && p.y==q.y; } int eqrect(Rectangle r, Rectangle s) { return r.min.x==s.min.x && r.max.x==s.max.x && r.min.y==s.min.y && r.max.y==s.max.y; } int rectXrect(Rectangle r, Rectangle s) { return r.min.xmin.x = r2.min.x; if(r1->min.y > r2.min.y) r1->min.y = r2.min.y; if(r1->max.x < r2.max.x) r1->max.x = r2.max.x; if(r1->max.y < r2.max.y) r1->max.y = r2.max.y; } ulong drawld2chan[] = { GREY1, GREY2, GREY4, CMAP8, }; /* * was used by libmemlayer/line.c; made static, instead of deleting it, * to avoid updating many binaries on sources. */ static int log2[] = { -1, 0, 1, -1, 2, -1, -1, -1, 3, -1, -1, -1, -1, -1, -1, -1, 4, -1, -1, -1, -1, -1, -1, -1, 4 /* BUG */, -1, -1, -1, -1, -1, -1, -1, 5 }; ulong setalpha(ulong color, uchar alpha) { int red, green, blue; red = (color >> 3*8) & 0xFF; green = (color >> 2*8) & 0xFF; blue = (color >> 1*8) & 0xFF; /* ignore incoming alpha */ red = (red * alpha)/255; green = (green * alpha)/255; blue = (blue * alpha)/255; return (red<<3*8) | (green<<2*8) | (blue<<1*8) | (alpha<<0*8); } Point ZP; Rectangle ZR; ```